ZUIKO DIGITAL 25MM X F=2.8

ZD pancake lens on test


MANUFACTURERS DESCRIPTION:

* Pancake Lens

* Compact design and lightweight

* 20cm closest focusing distance

The ZUIKO DIGITAL 25mm 1:2.8 (35mm equivalent focal length: 50mm) pancake lens accentuates the amazing compactness of the E-System. Featuring an extremely short-barrelled, lightweight design, this lens represents the perfect accompaniment for the E-420. With its overall compactness, the set-up reminds of the legendary improvement to mobility that the famous Olympus OM series provided.

TECHNICAL SPECIFICATIONS:

Focal length = 25 mm; Focal length (equiv. 35mm) = 50 mm

Lens configuration: 5 lenses in 4 groups

Aspherical glass elements = 1

Lens mechanism; floating focus mechanism

Angle of View = 47

Closest focusing distance: 0.2 m

Maximum image magnification 0.19 x (Four Thirds) / 0.38 x (35mm format)

Number of aperture blades = 7

Maximum aperture; 1:2.8

Minimum aperture; 1:22

Filter diamater = 43 mm

Dimensions; 64 mm , 23.5 mm length

Weight = 95 g

Compatible to Tele converter EC-20 - Yes

Compatible to Tele converter EC-14 - Yes

Compatible to Extension tube EX-25 - Yes

CHARTS:



Lens architecture and MTF charts courtesy of Olympus Imaging, Japan.


INTRODUCTION:

I've had this lens 'on order' from Olympus UK for a website review for months; this is a sure sign of how popular it has been in terms of sales. I understand the Olympus factory produced some 20,000 in a single run back in March 2008 and when commercially released it sold like hot cakes with demand outstripping supply. The factory has now caught up with demand.

BOX CONTENTS:

The first thing I see is the rather fetching lens cap; a screw in type 43mm diameter. After unscrewing it just once I see what a nuisance this will be in general use and understand why folks are seeking an alternative. A cap like this will soon go walk-about! There is no case supplied but I dare say the EC14 softcase (LSC 0710) will make a good home and these are normally available on Amazon.co.uk here for about 8.00 + postage. There is an idiot's guide of do's and don't's, a warranty card and that's about it.

HOODS & FILTERS:

Surprisingly there's no hood (Olympus make one specially but it's only available in Japan for some strange reason. The image on the left below is taken from the official Olympus site and imposed on the lens architecture diagram. If you can read Japanese you can see the whole page here).



A composite image of the lens hood from the Japanese site and section through lens with hood fitted.

The lens hood shown on the Japanese site appears to be nothing more than some sort of fancy step-down ring 43mm~34mm. My rough price conversion tells me the hood will cost around 22.00 plus postage - expensive. So I look in my oddments box (that all collectors have) and I find an empty 43mm filter ring about 5mm deep that I fitted to the 25mm pancake and into which I screw a hood from the Pen F 70mm x f=2.0 lens. The Pen F hood is 43mm too, but I thought I'd play safe and fit the extra 5mm to avoid any cut-off corners. So far I haven't noticed any vignetting. I assume generic floppy rubber hoods are available in 43mm fitting; if so it would be worthwhile trying one. While the front elements are set quite deeply in the ZD pancake lens I can see occasions where the sun might cause flare, so any hooding device will be welcome, contrived or Olympus designed.

I also have quite a few filters at 43mm from my Pen F days and a circular polariser (CPol) that I use on my C5050's extension/lens armour tube. While trying these on I note the mounting threads on the ZD25mm are unusually short requiring only 270~350 degrees of turn from start to tighten, depending on the thread. Because the CPol is turned in normal use I found this could result in the CPol falling off quite easily, so if you are going to use any filters please be aware of this.

PRESENTATION:

The lens itself is tiny and light weight (95g), but very well made. It is retrofocus in design (its focal length being smaller than its flange measurement) having 5 elements in 4 groups (the equivalent of an E-Zuiko in OM terms). Its lens design and architecture is simple (complex lenses present many problems not least coating issues) leading to good flare resistance. With a minimum close focus distance of 20cm (8") it should be a great all round companion. Its construction is mainly budget but it does not look cheap at all. The manual focus ring is rubber clad unlike other budget examples where this is made from of hard ribbed plastic, not rubber. The lens nomenclature is printed in white lettering directly on the lens barrel on its uppermost part when mounted and not on an embossed or printed 'plate'. No distance scale read-out window is provided. There is ribbing to the mounting grip ring and the usual red nipple acts as the mounting guide. Underneath is the serial number plate and it has 'Made in China' printed on the rear baffle. The front dress ring bears the typical nomenclature plus the filter size of 43mm. The mounting ring is stainless steel.

Manual focus is very smooth and being 'fly by wire' is generous in movement with accurate manual focus only limited by viewfinder screen size not the lens' racking sensitivity. In AF focus is quick and robust with little difference between use on the 'older' E-400 or the E-3. However, and as expected, low light AF is decidedly better on the E-3 body. I note that all focus is internal so the end tube does not rotate in use thus putting a smile on the face of polariser users.

Obviously the size of the pancake suits better the smaller machines like the E-4XX series making the E-400 combination almost pocketable. Its design configuration may be retrofocus but its aesthetics on an E-400 are retro too!



Above: the ZD25mm fitted to the E-400. Tiny and attractive.



And here's the ZD 25mm fitted to the E-3. Maybe not so aesthetically pleasing.


BARREL DISTORTION:

I set up the tripod indoors and just fill the frame with this test chart. I endeavour to have the chart level and plumb, as well as the camera. I do not use flash. When complete I mark the captured image horizontal with two red lines above and below the rendered top line of the chart. Here's the result:



This is quite a lot of barrelling but remember this is a wide angle lens so some barrel distortion is to be expected. Perhaps a little more than I'd anticipated though.


STANDARD TEST:

I set up the tripod to do some test shots against my normal target which is a stone gate pillar with a small house sign (landscape A4 size) that is some 220 feet from the camera-on-tripod position. I decide to compare the pancake against the ZD14-54mm set to 25mm at a selection of apertures. First I mount the ZD25mm.

For all sessions of testing I use the E-3 with these base settings: A mode, ESP, ISO = 100, WB AUTO, NR= OFF, S-AF, File = L Super Fine JPG, COMPENSATION = 0; tripod mounted and shutter tripped with RC-C1 (Generic version of RM1) remote.



This is my usual target shot.



Here are the first set of crops from the ZD25mm lens mounted on the E-3 in A mode with the lens set to f=2.8, 4.0, 5.6, 8.0, 11, 16. The day was dull and overcast; about 3.30 in the afternoon, it was not raining and was a typical UK overcast early autumn day with diffuse light behind a white sky.



This first set of three crops show how the lens performs wide open to f=5.6 and as you can see it is a tad soft wide open but soon sharpens up as the aperture is closed.



The second set of three crops show the results at f=8.0, 11 & 16. Certainly the mid range of f=5.6, 8.0 & 11 give the best results.



These results are generally in line with most other 'budget' or 'kit' lens offerings from Olympus and follow the accepted norm of being a tad soft to soft wide open, sharpening up rapidly and in sequence as the aperture is closed up to around f=11 and then softening again as diffraction sets in. During my time with the ZD25mm I found f=6.3 seemed to deliver the most consistent results.

COMPARISON WITH ZD14-54 at 25mm:

To give some perspective to the pancakes sharpness performance at this distance I repeat the test using the ZD14-54mm set to 25mm across the same aperture range as above. This will give a sense of comparison as I believe most E-system users are aware of this 'professional' grade lens performance.



This first set of three crops show a very similar level of sharpness across the apertures up to f=4.0. I think the ZD14-54mm results at f=3.1 are worse than the little prime wide open, being softer. But it soon sharpens up as the aperture is closed and shows virtually the same performance at the remaining apertures as the prime pancake.





This second set of three crops show how the lens performs from f=5.6 to f=16 and again I can see little difference between its performance and that of the pancake. If I were to be super critical I'd say at f=8.0 the ZD14-54mm is marginally sharper than the pancake, but I have the advantage of seeing the full size images.


OBSERVATIONS ON STANDARD TEST:

Comparing the two sequences above you can see there is not a great deal of difference in performance between the prime and the zoom. Both are soft wide open at 25mm and both sharpen up much the same as the apertures are closed. There is a slightly better performance from the ZD14-54mm at f=8.0 but you need to see the full images to discern the difference. For all intent and purpose they perform at a similar level.

Bear in mind that we are comparing a 'Pro Grade' zoom to a 'budget' grade prime (and a simple optical design at that) with a pretty large price difference too. That the little pancake holds its own against the highly acclaimed (not necessarily by me) 'Pro' ZD14-54mm zoom is a good result and surpasses my expectations.

Just a note about my example of the ZD14-54mm: Some of you will recall I had to return my original E-1 and lens for re-calibration. I have never been entirely happy with my ZD14-54mm since those early days. That said it does perform well against other 'Pro' grade lenses in various tests, so perhaps my skepticism is unfounded.


COMPARISONS WITH OTHER LENSES AT 25mm:

Perhaps it might be interesting to do some further direct comparisons of performance of this lens with other lenses, both ZD and OM. For this exercise I'm going to use the 25mm Pancake against the ZD18-180mm at 25mm and the OMZ 24mm x 2.8. As we know all these lenses perform best stopped down, so I'm going to restrict this test to wide-open, f=5.6 and f=11.

Here's a different target (the notice in the window is 35 foot from the camera) with the objective being able to read the notice, so I've cropped out the area shown in red and put the three crops per lens onto one image for direct comparison. The title of the small notice reads 'Register Now' and towards the bottom are a series of tiny camera images in an arc.



My target.



ZD 25mm Results: Here you can see that the centre image sharpens at f=5.6 but is 'just' not readable. Contrast is a little down in my eyes leading to a 'loss' of perceived sharpness.



ZD 18-180 at 25mm Results: These are marginally better than the ZD25mm, but almost readable. Contrast about right to my eyes giving the impression of better sharpness.



OMZ 24mm Results: About the same as the 18-180, perhaps slighly less readable. Contrast is variable with aperture and exposure - see the centre crop, with variable apparent sharpness.

OBSERVATIONS ON ABOVE COMPARISONS:

There's not really a whisker to put between these results and shows how similar the optical performance is between the three lenses. The Pancake results for this test are probably marginally worst of the three followed by the OMZ 24mm and the ZD18-180 coming marginally first. But believe me when I looked at the full size images there's virtually nothing between them. And, when you look at the results from the first test (stone pillar) there was little difference between the ZD25mm and the ZD14-54 set to 25mm.

Notice the different contrast rendering of each lens with the ZD18-180 giving the best contrast and the OMZ 24mm the most inconsistent. Contrast plays a huge role in one's perception of sharpness; the more contrasty the image the more the perceived level of sharpness.

From this I've got to conclude that there is really hardly any difference between any of the budget and 'Pro' grade lenses when it comes to optical performance in these tests, at these set distances and these set apertures. Of course the big difference lies in how fast the lenses are and the degree of weatherproofing they enjoy, and that's what you pay for when you upgrade to 'Pro' level lenses. When you step up to the higher level still you get mid aperture performance wide open - hence the prices of the 'Top Pro' models.

This result repeats itself in nearly all the tests I undertake and I am always pleased to see so little difference between the grades of lenses and I think Olympus should be congratulated on the optical quality of their budget offerings. They certainly do not optically 'cripple' their lower grade lenses to force users to upgrade. I applaud this attitude.


EXAMPLES:

I set off to look for photo opportunities to test the pancake. Here's what I found:



Farm stile: I spotted this unusual notice asking folk to walk in single file to maximise the grass. This shot was taken at f=4; 1/160th; comp = 0; ISO 100; all else standard; with CPol.

There's a full size untouched JPG of the above to download for your later study (6.5MB file) here



Crop: From upper right corner - some quite heavy areas of purple fringing. If the sky was whiter this defect would be worse.



Moss on wall: Here I'm showing the effect of defocusing when using the lens wide open. The out of focus area is rendered nicely, if not brilliantly, showing the restriction of both f=2.8 and the x2 effect of the sensor. F=2.8; 1/125th; Comp = -0.3; ISO = 100; all else standard, no filter.



Log harvest: This is for you to judge centre & corner sharpness. Image taken from about 3 feet at f=6.3; 1/320th; Comp = -0.3; ISO 100; all else standard; no filter.

There's a full size untouched JPG of the above to download for your later study (6.5MB file) here



Crop 1: Taken from centre. The little pancake is a pretty good performer in the sharpness stakes. Not bitingly sharp but sharp enough.



Crop 2: Taken from upper left corner. To my eyes there's just a tad of softening as the corners approach, but you need this type of close work shot to show it. To be honest you are not going to notice this and in any case everyone has different ideas about sharpness either applied in camera pre-exposure, or in post processing. I think it would be churlish to criticise this.



Lower Arkengarthdale: A typical bit of local scenery taken at f=6.3; 1/125th; Comp = 0; ISO 100; all else standard; CPol used to enhance the skyscape and cut through the bit of late summer haze.



Crop: Taken from lower right corner. In this example the corner is as good as the centre and looks pretty sharp to me - look at the windows in the house. You can also see the effect of the CPol, the non-sky areas are over-saturated.

OBSERVATIONS ON EXAMPLES:

I have little further to add. These images speak for themselves. I rather like the pancake and the discipline it brings by having to use your feet to zoom in and out. I'm not entirely convinced that 25mm (50mm equivalent) was the 'best' possible choice of focal length for Olympus' first pancake prime as I find 50mm quite boring to be honest, but that's just my opinion. My favourite lens from Pen F days was the 60mm x f=1.5 which has the 35mm equivalent of an 85mm, so its portrait territory, but very useful for general scenery. As you probably know I'm no lover of wide-angle stuff mainly because of where I live; put a wide angle lens on here and you simply get more green at the bottom and more blue at the top!! (Yes, it's much more complex than that!) But we are all different.


GENERAL PHOTOGRAPHY:

To sum up, here's a few shots I took around my garden that try and show various other lens attributes. As already said, the pancake is not a 'bitingly sharp' lens like the 35mm & 50mm Macro's but it is sharp enough. And we really shouldn't get hung up about a modicum of unsharpness at pixel level. This lens was designed to be light and slim and primarily to enhance the 'smallness' of the E-4XX series of cameras, which it does admirably. And of course this applies to anything else you mount the pancake on too.



This is a garden shot of some Hawthorn berries taken wide open to show sharpness at the point of AF which was the three berries 2/3rds up and centre. More so it endeavours to show the quality and depth of defocused area which, to me is acceptable, but not award winning. There's a reasonable amount of separation but the subject does not 'leap' off the page.

There's a full size untouched JPG of the above to download for your later study (6.5MB file) here



And for OM lovers everywhere here's almost the same shot taken with the OMZ 24mm x 2.8 wide open - just a bit more sunshine. You can see some rather ugly out of focus highlights which reproduce the OM lens aperture blade signature; however the general rendering of the defocused area (to my eyes anyway) is a little better with more separation and the subject does 'stand off' the page. What do you think?



Back to the ZD25mm, this time at f=6.3 (the sweet spot for sharpness in my opinion) with the top left corner exposed against a white sky to show any purple fringing - which it does but it's reasonably well controlled.



And here's the crop at 100% from the bottom left corner. This is good and sharp; not quite up to ZD50mm Macro standards but really, good enough.


OPINION:

To be honest, I harboured some doubts about the ZD pancake. These were probably born out of my previous experiences with the Pen F/FT/FV 38mm x f=2.8 pancake that was OK'ish and the later, infamous, OM 40mm x f=2.0 'pancake', which was a total dog. Strangely, the ZD pancake is (architecturally) very similar to the 40 year old Pen F pancake, both being 5 element in 4 group construction and both sharing a 43mm filter ring. One of these days I'm going to directly compare the results.

But I'm glad to report my fears are unfounded; the ZD Pancake is a super little lens. It handles well, has good AF and manual capabilities, is innately a good close-focus lens, is sharp enough for 95% of anyone's applications and does exactly what you'd expect. It has pleased me no end! I shall be adding one to my personal ZD armoury when I can afford one.

SHARPNESS: Good to Very Good: I was surprised and delighted to see these levels of sharpness.

CONTRAST: Good: Perhaps not quite up to the standards of other Olympus lenses; down a tad.

COLOUR RENDERING: Good to Excellent: No issues here.

RESOLUTION: Good to Very good. Bearing in mind its 'budget' status.

CHROMATIC ABBERRATION: There is a touch of CA (PF). Not dramatic and easy to remove but it is there.

BARRELLING: Average: Remember this is a wide angle lens and is prone to a bit of barrel. Acceptable?

FLARE: Generally I did not find flare a major issue unless straight into the sun and even then no huge problems. My improvised hood helped.

HANDLING: Good. My only comment is it is quite difficult to mount/unmount as there's so little lens to get hold of!

FINAL COMMENTS:

For prime lovers this lens offers a little more - its a pancake! You get your prime wish and it is small and neat into the bargain. Whether there's the will at Olympus to deliver more primes - let alone pancakes - remains to be seen. Personally I doubt we'll see another pancake as the optical design can only sit within tight boundaries around the 35-55mm equivalent focal length range. I have hopes for more traditional primes such as ZD11mm, ZD18mm and ZD35mm with bright f=2.0 apertures, but these are already covered by some pretty good zooms. Perhaps Olympus develops the zooms while Panasonic look to the primes?

RECOMMENDATIONS:

For the money this little lens performance is very good value. Any 4/3rds user who has a shine for a prime lens or who came up through the standard OM system route will be very happy with the ZD25mm x 2.8. It's a bit like going home!

Will I be buying one - Yes.

ACTUAL PRICES (MRRP):

UK 199; Available on-line for about 170; Best US price $220 at B&H Photo.


NOTE: This article seeks nothing other than to inform. Only you can decide what equipment you want/need for your use. Occasionally I test cameras/lenses on loan from Olympus UK for website review; the ZD25mm Pancake is one such piece. However; I have nothing to gain or lose by publishing this article, photographs, examples or opinion. Olympus UK have no input into this review.


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Posted September 2008 Copyright © 2004/2005/2006/2007/2008 John Foster